CHEMISTRY COMMUNITY

Jessica Nunez 1I

I understand Step #2 is the slow step, but how do we know if Step #1 is faster than Step #3 (or vice versa)?

Jessica Nunez 1I

By using this notation, we assume that E°cell > 0 and that the Gibbs free energy is negative.

Jessica Nunez 1I

Will we always be given the proposed reaction mechanisms?

Jessica Nunez 1I

If there is only one step in the reaction, do we assume it is the slow step?

Jessica Nunez 1I

The differential rate law for the a zero-order reaction is k[A]^0 and the integrated rate law is [A] = -kt + [A]^0

Jessica Nunez 1I

2C4H6(g) → C8H12(g) The dimerization reaction of butadiene is second order and has a rate constant of 0.0140M-1·s-1 at 500˚C. Determine the C4H6 concentration after 115.0 seconds if the initial concentration of C4H6 is 0.0500 M. I tried solving this part of the problem, but my solution doesn't quite...

Jessica Nunez 1I

What is the difference between the zero-order reaction graph and the first-order reaction graph?

Jessica Nunez 1I

As mentioned, the key words, external pressure, helped me identify that pressure is constant.

Jessica Nunez 1I

The question should specify if the reaction is in acidic or basic conditions, but a reaction in acidic conditions usually contains H+ while a reaction in basic conditions usually contains OH-

Jessica Nunez 1I

I believe standard potentials occur when the substances are in their stable states at 25 degrees Celsius.

Jessica Nunez 1I

I think it's because those reactions take place in acidic solution since H+ is part of the reaction.

Jessica Nunez 1I

An example of finding the oxidation state could be MnO4-. We know the overall charge of MnO4- is -1 and oxygen as O4 has a charge of -8, so we only need to find the charge of Mn.

x + 4(-2) = -1

x-8 = -1

x = +7

The charge of Mn is +7.

Jessica Nunez 1I

As mentioned, the oxidation state of oxygen as a diatomic molecule (O2) is zero. However, when oxygen is in a compound, the charge varies between -1 and -2.

Jessica Nunez 1I

When referring to the voltage of redox potential, how do we know which reaction is the anode and which reaction is the cathode?

Jessica Nunez 1I

I am confused as to how the chemical equation on 14.1, Part D was balanced.

Jessica Nunez 1I

Based on the learning objectives listed for Chapter 9, it would be helpful to know how to derive the equation.

Jessica Nunez 1I

Do all diatomic molecules have 0 standard Gibbs free energy?

Jessica Nunez 1I

What is the total entropy change of a process in which 40.0 kJ of energy is transferred as heat from a large reservoir at 800. K to one at 200. K?

For 9.5, the student solutions manual uses a negative sign for (delta)S = -40000 J/800 K, and I do not know why.

Jessica Nunez 1I

In order to find W, I think it would help drawing out different Lewis structures to identify the various ways the molecule can exist.

Jessica Nunez 1I

Gibbs free energy is amount of energy available to do work, and it can be used to predict whether a reaction will be spontaneous or not. If delta G is negative, then the reaction will be spontaneous in the forward reaction (meaning that the reactants have enough energy to move the reaction forward)....

Jessica Nunez 1I

I would also suggest you using 273.15 to avoid any discrepancies in your answer.

Jessica Nunez 1I

In addition, if ΔG is negative, then it means that the reactants have more energy than the products which will allow the reaction to move forward (occurs spontaneously). If ΔG is positive, then it means that the reactants have less energy than the products, which will require an input of energy (doe...

Jessica Nunez 1I

As mentioned, if the work done is reversible, then you would use w = -nRTln(V2/V1). If the work done is irreversible, then you would use w = -P(ext)ΔV.

Jessica Nunez 1I

The heat capacity increases with molecular complexity. As more atoms are present in the molecule, there are more possible bond vibrations that can absorb added energy.

Jessica Nunez 1I

Celsius and Kelvin can be used interchangeably in this case because the degree change in Celsius is equivalent to the degree change in Kelvin.

Jessica Nunez 1I

Examples of open systems include a living plant, gasoline burning in an automobile engine, and boiling water without a lid. These systems are open systems because they freely allow energy and matter to be transferred in an out of the system.

Jessica Nunez 1I

A pressure cooker containing 100.0 g of liquid water at 25 C is placed on the stove until all water becomes superheated steam at 121 C. Assume no steam escapes the pressure cooker. a) Find q from 25C to 100C b) Find q during boiling c) Find any other heat gained or lot by the water as it goes from 2...

Jessica Nunez 1I

According to page 273, the first law of thermodynamics (delta)U = q + w mentions that the internal energy of an isolated system is constant; however, I am unsure if we can assume pressure is constant.

Jessica Nunez 1I

NO2 would have higher molar heat capacity because heat capacity increases with molecular complexity. This means that as more atoms are present in the molecule, there are more possible bond vibrations that can absorb added energy.

Jessica Nunez 1I

As mentioned, R is the gas constant which is equal to . . .
8.314 J.K^-1.mol^-1 = 8.206 x 10^-2 L.atm.K^-1.mol^-1 = 8.314 x 10^-2 L.bar.K^-1.mol^-1 = 62.364 L.Torr.K^-1.mol^-

Jessica Nunez 1I

As mentioned, using one unit over the other does not matter because the change in temperature would be the same, but I would just stick to the units that are initially given.

Jessica Nunez 1I

Identify the following systems as open, closed, or isolated: (a) coffee in a very-high-quality thermos bottle; (b) coolant in a refrigerator coil; (c) a bomb calorimeter in which benzene is burned; (d) gasoline burning in an automobile engine; (e) mercury in a thermometer; (f) a living plant. I'm a ...

Jessica Nunez 1I

To add on, an isolated system has no contact with surroundings. However, in the case of the thermometer, the heat of the mercury can be transferred to or from the thermometer.

Jessica Nunez 1I

Right. Based on Dr. Lavelle's email, I don't think titrations will be covered on the final.

Jessica Nunez 1I

In addition, when the pH is 7 (neutral), it implies that [H3O+] is 1.0 x 10^-7 and [OH-] is 1.0 x 10^-7--all which equals 1.0 x 10^-14 when they are multiplied together.

Jessica Nunez 1I

Fundamentals J was covered, and it is useful to get practice and some background on Chapter 12 concepts.

Jessica Nunez 1I

I think we would need to assume CaCO3 is the limiting reactant based on what the problem tells us. If we had to find the limiting reactant, I believe they would give us the mass for both reactants.

Jessica Nunez 1I

According to the Acids and Bases outline, we have to know how to identify Bronsted acids and bases + Lewis acids and bases, so I don't think we need to worry about Arrhenius acids and bases.

Jessica Nunez 1I

I'm a little confused on how you would determine the pH given this information.

Rank the following solutions in order of increasing pH:
(a) 1.0 10^-5 M HCl(aq);
(b) 0.20 M CH3NH3Cl(aq);
(c) 0.20 M CH3COOH(aq);
(d) 0.20 M C6H5NH2(aq). Justify your ranking.

Jessica Nunez 1I

To add on, K = Kp is for gases and it is denoted by the units atm (bar, torr, Pa etc.). Kc is for concentration which is denoted by molarity units.

Jessica Nunez 1I

I'm a little confused on how to solve this problem that's in the Chemical Equilibrium Part 2 Module. Consider the following reaction at 1200 K, for which you know Kc = 1.7 x 10-3. Br2 (g) ⇌ 2 Br (g) Your experimental setup is able to measure the equilibrium concentration of Br2 based on its color, b...

Jessica Nunez 1I

In general, you would use P when referring to gases. However, this does not mean you will use P whenever you have gases. If it's atm (bar, torr, Pa, etc.), then you would use Kp. If you have M or any other concentration units, then you would use Kc.

Jessica Nunez 1I

Sn-Cl2 only has 6 valence electrons because the formal charge of the structure would be 0, and that is the ultimate goal when drawing Lewis dot structures.

Jessica Nunez 1I

I don't think there is a difference between bent and angular.

Jessica Nunez 1I

I don't think we need to write out the electron configuration in this notation unless it is asked. However, I think this notation is good just to see how orbitals are filled up.

Jessica Nunez 1I

Are there any exceptions to the Hybridization guidelines given in lecture?

Jessica Nunez 1I

The correct answer is stoichiometric coefficients.

Jessica Nunez 1I

The formal charge could be indicated by a number, depending on the answer you get from using the formal charge equation, which is V - (L + B/2).

V: # of valence electrons in free atom
L: # of electrons present on bonded atom as lone pairs
B: # of bonding electrons on atoms

Hope this helps!

Jessica Nunez 1I

To add on, the atomic radius increases down a group because electrons occupy sub-shells with increasing quantum number, which suggests that the atomic radius increases as the quantum number increases.

Jessica Nunez 1I

I would say that option 1 is correct because the correct electron configuration of Chromium is [Ar](3d^5)(4s^1). When the electron is ionized, the electron taken out is from the s-orbital. I believe the reasoning will be provided for all elements in the d-block. However, we need to be most concerned...

Jessica Nunez 1I

Does this mean that there is a direct relationship between the number of electrons and the size of the radius?

Jessica Nunez 1I

Like others have said, putting 3d before 4s in electron configuration will help us understand how orbitals fill up. However, is it wrong if we put 4s before 3d?

Jessica Nunez 1I

If the problem asks for the wavelength in nanometers, I would provide it in nanometers. However, when you are solving the problem, I would use meters since the SI unit is meters and the values of the other constants are given in meters. Hope this helps!

Jessica Nunez 1I

For this week, you can still turn in homework from Chapter 1 as long as the problems are not the same ones you turned in last week. Next week, we can turn in homework from Chapter 2.

Jessica Nunez 1I

Sig figs are mainly important in the final answer, so do not worry about rounding in the middle of a problem. For the final answer, I would determine the number of sig figs based on the number that has the least number sig figs in the original problem.

Jessica Nunez 1I

With respect to Part C, is there a relationship between the extent of change in an electrical field and the frequency of electromagnetic radiation?

Jessica Nunez 1I

Right. Since 3.20 has the least number of sig figs based on the original problem, your final answer should have three sig figs as well. Hope this helps!

Jessica Nunez 1I

Yes. If a problem states that nitrogen is produced in their elemental form, then we can assume the product is gaseous nitrogen and that it is a diatomic molecule (N2).

Search found 58 matches